Convertible sofa bed

ABSTRACT

A sofa bed traversable between a sofa and bed configurations is disclosed herein. It has a folding mechanism having first and second pairs of link members rotatably attached to a backrest and support members on left and right sides of the back rest. Via the first and second link members, the back rest is transitionable between the sofa configuration and the bed configuration. A seat base is movable up and down at an angle via a sliding mechanism or a five bar parallelogram linkage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Provisional Application No. 62/899,947, filed on 2019 Sep. 13, and is a continuation in part of U.S. patent application Ser. No. 16/052,578, filed on 2018 Aug. 1, which claims the benefit of U.S. Provisional Application No. 62/540,068, filed on 2017 Aug. 2, the contents of which are expressly incorporated herein by reference.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND

The embodiments and aspects described herein relate to a sofa bed with a folding mechanism that facilitates conversion from a sofa to a bed, and vice versa.

Folding beds, particularly sofa beds, have been desirable in tight living spaces where utilizing a single living space for multiple purposes may be optimal to save space. However, there are various deficiencies in current folding beds, including the compromise of either giving up comfort for space or practicality for comfort in an attempt to be functional in tight spaces or multipurpose rooms. Thus, there is a need for an improved sofa bed.

Accordingly, there is a need in the art for a sofa bed that improves on the practicality and comfort of current sofa beds.

BRIEF SUMMARY

The various embodiments and aspects described herein address the needs discussed above, discussed below, and those that are known in the art.

The present disclosure is directed to a sofa bed having one or more mechanisms (e.g., a folding mechanism and a sliding mechanism) that allow the sofa bed in sofa configuration to have a backrest and seat portion so that the sofa bed can be used as a sofa, and allow the sofa bed to be traversed to a bed configuration to have a conventional mattress that stays locked in place. Additionally, a benefit of the sofa bed is that the sofa bed described herein with a standard twin or twin xl mattress does not require any sort of anchoring of a frame of the sofa bed to a wall or floor.

There may be a convertible sofa bed with a folding mechanism capable of traversing the sofa bed between a sofa configuration and a bed configuration. The sofa bed may have a left support member and a right support member, both configured to rest on an underlying surface, a backrest having a left end and a right end. The backrest may be horizontally disposed between the left support member and the right support member, wherein the left end is attached to the left support member and the right end is attached to the right support member. The backrest may be configured to pivot up when the sofa bed is traversed to the sofa configuration and may pivot down when the sofa bed is traversed to the bed configuration. the backrest may have a front side and a rear side. The rear side may define a bed frame. The bed frame may be engageable with a mattress. The sofa bed may further have a seat base having a left end and a right end attached to the backrest. the seat base is receptive to at least one seat cushion.

The folding mechanism of the sofa bed may have a left first link member rotatably attached to the left backrest end and the left support member, and a right first link member rotatably attached to the right backrest end and the right support member. The left and right first link members may push upward on the backrest when the sofa bed is in the bed configuration. The left and right first link members may be shorter than the left and right second link members. The folding mechanism may further have a left second link member rotatably attached to the left backrest end and the left support member and a right second link member rotatably attached to the right backrest end and the right support member. The pivot points of the rotatable attachment of the left and right first link members to the left and right backrest ends may be at a first height above the underlying surface and the pivot points of the rotatable attachment of the left and right second link members to the left and right backrest end may be at a second height, the first and second heights being within 3 inches of each other. The first and second heights may be equal to each other. The left and right first link members may be about 3.5 inches. The left and right second link members may be about 6.5 inches. The left and right second link members may be about twice in length than that of the left and right first link members. The left and right second link members may push downward on the backrest when the sofa bed is in the bed configuration.

The sofa be may further have a left front link member rotatably attached to the left backrest end and the left seat base end and a right front link member rotatably attached to the right backrest end and the right seat base end. The left and right front link members may be between about 6 inches and 18 inches. When the sofa bed is traversed to a bed configuration or a sofa configuration, the left front link member and the right front link member may be configured to rock about the seat base, and the backrest may be configured to rotate about the left link member and the right link member. The pivot points of the rotatable attachment of the left and right front link members to the left and right backrest ends may be at a first height above the underlying surface and the pivot points of the rotatable attachment of the left and right front link members to the left and right seat base ends may be at a second height, where the first height may be higher than the second height.

The sofa bed may further have a sliding mechanism. The sliding mechanism may have left first and second track members connecting the left seat base end to the left support member, and right first and second track members connecting the right seat base end to the right support member. The left and right track members may be parallel to each other. The left and right first and second track members may be left and right first and second rails that are receptive to left and right first and second sliding members that are slidably engageable with the left and right first and second rails. The left first and second rails may be mounted on an inner surface of the left support member and the right first and second rails may be mounted on an inner surface of the right support member. The left and right first rails and the left and right second rails may be parallel to each other and at an angle to a vertical plane. The left first and second sliding members may be mounted on the left seat base end and the right first and second sliding members may be mounted on the right seat base end. The left and right first sliding members and the left and right second sliding members may also be parallel to each other at the angle to the vertical plane. The mounting angle of the left and right first and second rails and the first and second sliding members may be between about 6 degrees to 20 degrees. The left and right first and second rails may be of equal length. Further, the sliding mechanism may be lockable with a optional stopping mechanism. The stopping mechanism may be a spring loaded latch.

In bed configuration, the left and right first and second link members may create a reaction force couple that counters a summation of moments created by the weight of the seat base, weight of the backrest, and a weight of a person resting on the backrest so that the sofa bed remains in the bed configuration. The left and right first link members may be vertical and parallel to the left and right second link members to lock the backrest at the bed configuration. In sofa configuration, the seat base may optionally be locked at the sofa configuration by means of a locking mechanism. Also, even without a locking mechanism, a summation of the weights of the backrest, and the mattress, may be more than the weight of the seat base so that the backrest stays in the sofa configuration as well.

There may further be a method of traversing a convertible sofa bed with a folding mechanism from a sofa configuration to a bed configuration. The method may include a set of steps, wherein a first step may be unlocking a lock that holds a seat base and a backrest at a sofa configuration. The lock may be unlocked by disengaging a spring loaded latch from a latch slot. A second step may be rotating a backrest having a rear side defining a bed frame to a horizontal position so that the rear side faces upwards. An application of a horizontal pulling force on the backrest, or a downward force on the seat base, may be necessary to initiate the rotation of the backrest. The rotating step may be aided by left and right front link members connecting the backrest to the seat base rocking towards the seat base and rotating the backrest and left and right first and second link members attached to the left and right backrest ends to oscillate the backrest about a left joint and a right joint that join the left and right backrest ends to the left and right second link members and a left joint and a right joint that join the left and right backrest ends to the left and right first link members until the backrest is horizontal. A third step may be lowering the seat base so that the backrest is disposed above the seat base when the sofa bed is in the bed configuration. Lowering the backrest and seat base may be assisted by a spring so that a weight of the seat base does not cause the backrest and the seat base to inadvertently and too quickly drop to the bed configuration. For example, spring (e.g., gas spring, coil spring, elastic member, . . . etc.) may be connected to the back rest and the arm rest. The compressibility of the cushions can also serve to help dampen the impact should the backrest and the seat base drop down too fast. A fourth step may be positioning left and right first link members vertical and parallel to left and right second link members to lock the bed frame at the bed configuration.

As indicated above, the application of a horizontal pulling force on the backrest or a downward force on the seat base, may be necessary to initiate the rotation of the backrest. The downward force on the seat base can unlock the back rest in that the downward force on the seat base has a horizontal force component in the same direction as that as arrow. In this regard, the downward force will also move the backrest laterally in the direction of arrow and skew the link members as discussed herein to unlock the backrest.

Additionally, there may be a method of traversing a convertible sofa bed with a folding mechanism from a bed configuration to a sofa configuration. The method may include a set of steps, wherein a first step may be pulling a bed frame defined by a backrest laterally to orient left and right first link members to left and right second link members for unlocking the sofa bed from the bed configuration. The bed frame may be pulled until the left and right first link members are no longer at a 90-degree angle to a horizontal plane. Pulling the bed frame may involve applying a force on the bed frame that has a horizontal magnitude. A second step may be rotating the bed frame upward. Rotating the bed frame upward may involve applying a force on the bed frame that has a vertical magnitude. A third step may be raising a seat base. The seat base may be raised by sliding left and right first and second sliding members at an angle to the vertical plane along left and right first and second rails. The step of raising the seat base may be assisted by a link. Optionally, a spring may be used to help with the transition of the sofa bed to the sofa configuration. A fourth step may be locking the seat base and the backrest to a sofa configuration. The seat base may be locked by engaging a spring loaded latch with a latch slot.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which:

FIG. 1 is a perspective skeleton view of a sofa bed in sofa configuration.

FIG. 2 is a perspective skeleton view of the sofa bed shown in FIG. 1. having begun its conversion to bed configuration.

FIG. 3 is a perspective skeleton view of the sofa bed shown in FIG. 2. further into its conversion to bed configuration.

FIG. 4 is a perspective skeleton view of the sofa bed shown in FIG. 1 in bed configuration.

FIG. 5 is a side view of the sofa bed shown in FIG. 1 with a transparent right support member and in sofa configuration.

FIG. 6 is a side view of the sofa bed shown in FIG. 5 about having begun its conversion to bed configuration.

FIG. 7 is a side view of the sofa bed shown in FIG. 6 further into its conversion to bed configuration.

FIG. 8 is a side view of the sofa bed shown in FIG. 7 further into its conversion to bed configuration.

FIG. 9 is a side view of the sofa bed shown in FIG. 8 further into its conversion to bed configuration.

FIG. 10 is a side view of the sofa bed shown in FIG. 9 further into its conversion to bed configuration.

FIG. 11 is a side view of the sofa bed shown in FIG. 10 further into its conversion to bed configuration.

FIG. 12 is a side view of the sofa bed shown in FIG. 11 further into its conversion to bed configuration.

FIG. 13 is a side view of the sofa bed shown in FIG. 12 further into its conversion to bed configuration.

FIG. 14 is a side view of the sofa bed shown in FIG. 13 further into its conversion to bed configuration.

FIG. 15 is a side view of the sofa bed shown in FIG. 14 further into its conversion to bed configuration.

FIG. 16 is a side view of the sofa bed shown in FIG. 15 in bed configuration.

FIG. 17 is a perspective view of a sliding mechanism of the sofa bed in bed configuration, as shown in FIGS. 4 and 15.

FIG. 18 is a perspective view of the sliding mechanism shown in FIG. 17 of the sofa bed in sofa configuration, as shown in FIGS. 1 and 5.

FIG. 19 is a flowchart of a method of converting the sofa bed in sofa configuration (shown in FIG. 1) to the bed configuration (shown in FIG. 3).

FIG. 20 is a flowchart of a method of converting the sofa bed in bed configuration (shown in FIG. 3) to the sofa configuration (shown in FIG. 1).

FIG. 21 is a partial perspective partial view of an embodiment of the sofa bed with a seat base folding mechanism in the sofa configuration.

FIG. 22 is a partial perspective partial view of the sofa bed of FIG. 21 in the bed configuration.

FIG. 23 is a partial perspective partial view of the sofa bed of FIG. 21 having begun its transition from the bed configuration to the sofa configuration.

FIG. 24 is a side view of the sofa bed of FIG. 21 in the bed configuration.

FIG. 25 is a side view of the sofa bed shown in FIG. 24 further into its conversion to sofa configuration.

FIG. 26 is a side view of the sofa bed shown in FIG. 25 further into its conversion to sofa configuration.

FIG. 27 is a side view of the sofa bed shown in FIG. 26 further into its conversion to sofa configuration.

FIG. 28 is a side view of the sofa bed shown in FIG. 27 further into its conversion to sofa configuration.

FIG. 29 is a side view of the sofa bed shown in FIG. 28 further into its conversion to sofa configuration.

FIG. 30 is a side view of the sofa bed shown in FIG. 29 further into its conversion to sofa configuration.

FIG. 31 is a side view of the sofa bed shown in FIG. 30 further into its conversion to sofa configuration.

FIG. 32 is a side view of the sofa bed shown in FIG. 31 further into its conversion to sofa configuration.

FIG. 33 is a side view of the sofa bed shown in FIG. 32 further into its conversion to sofa configuration.

FIG. 34 is a side view of the sofa bed of FIG. 33 in the sofa configuration.

FIG. 35 is a flowchart of a method of converting the seat base from the down position (shown in FIG. 24) to the up position (shown in FIG. 34).

FIG. 36 is a flowchart of a method of converting the seat base from the up position (shown in FIG. 34) to the down position (shown in FIG. 24).

DETAILED DESCRIPTION

The various aspects of the sofa bed described herein may relate to a sofa bed wherein the sofa bed is convertible between a sofa configuration and a bed configuration. In the bed configuration, the sofa bed is placed into a position where a user can lay down on a standard mattress (e.g., twin or twin xl). In the sofa configuration, the mattress is moved out of the way so that the user can sit on seat cushions. The sofa bed does not require that a frame of the sofa bed be anchored to a floor or wall.

FIGS. 1-4 show a perspective and skeleton view of a sofa bed 10 in sofa configuration (see FIG. 1), transition configuration (see FIGS. 2-3), and bed configuration (see FIG. 4) resting on an underlying surface 12 with left and right support members 20, 22, which may also be referred to as left and right armrests 20, 22. It will be appreciated that the term “armrest” is for exemplary purposes only and not intended to be limiting. It is expressly contemplated that the sofa bed 10 may have left and right support members 20, 22 that are not armrests. The support members or armrests 20, 22 may be constructed out of one or a combination of materials commonly used in building sofa frames such as wood, artificial wood, molded plastic, aluminum and steel or any other durable, flexible, and/or resilient material. The armrests 20, 22 may be further padded and layered with linen fabric, corduroy, or leather depending on stylistic and comfort needs. Materials such as foam, down, feathers, fabric or a combination thereof may be utilized as padding.

The sofa bed 10 may have a backrest 30 (see FIGS. 1 and 2), a seat base 50 (see FIGS. 1 and 2), a folding mechanism 100 (see FIG. 5), and a sliding mechanism 110 (see FIG. 17). FIGS. 5-16 show the folding mechanism 100, and FIGS. 17 and 18 show the sliding mechanism 110 in further detail and how they function, which will be discussed below. The backrest 30 and the seat base 50 may be constructed out of one or a combination of materials commonly used in building sofa frames such as wood, artificial wood, molded plastic, steel or any other durable, flexible, resilient metal. Preferably, the backrest 30 may have a width of between about 30 to 60 inches (preferably 40 inches). The seat base 50 may have a width of between about 18 to 30 inches (preferably about 24 inches). Other dimensions are also contemplated. The folding mechanism 100 and sliding mechanism 110 may be constructed out of a load bearing material such as wood, steel, plastic, metal, any material with similar mechanical properties, or a combination thereof.

Also shown in FIG. 4, the rear side 38 of the backrest 30 may include a bed frame 40. The bed frame 40 may receive a bed. The rear side 38 may be flat wood, a wire spring grid, or incorporate other suspension arrangements known to one of ordinary skill in the art. The bed frame 40 may hold a mattress 42. The bed frame 40 shown in FIG. 4 is shown with side support, but that is optional. The bed frame 40 may be flat without side supports. The height of the backrest 30 may depend on the thickness of the mattress 42 held by the bed frame 40. Preferably, the backrest 30 may have a height between about 4 to 16 inches. The bed frame 40 may have ribbed inner walls to secure the mattress 42 in place to prevent the mattress 42 from falling out of the bed frame 40 when the sofa bed 10 is in sofa configuration, and when the sofa bed 10 is being transitioned into a bed configuration. The bed frame 40 may further utilize other fastening mechanisms known in the art to hold the mattress 42 such as hooks and loops, hooks, or string ties. The mattress 42 may be one of a range of commercially available mattresses such as innerspring, memory foam, latex, or gel. The combination of type of mattress 42 and rear side 38 may be chosen by the user based on comfort, health issues, or the need to be cost-effective. The mattress 42 size may be twin xl or twin, which are standard mattress size terms used in the art. Two or more sofa beds 10, in bed configuration may be joined side-to-side to form a queen, king, or California king size bed.

The length of the backrest 30 may be between about 70 inches and 90 inches, depending on the mattress size the bed frame 40 can accommodate. The seat base 50 may be suitable to put seat cushions 56 on. The seat cushions 56 may be a single piece or multiple pieces and cover the entirety of the seat base 50, and may have padding made of foam, down, feathers, fabric or a combination thereof and may have a linen fabric, corduroy, or leather cover. The height of the seat base 50 may depend on the thickness of the seat upholstery, or cushions 56. The length of the seat base 50 may be equal to that of the backrest 30. The length of the seat base 50 may be between about 70 inches and 90 inches. When the sofa bed is in the bed configuration, the mattress support surface may be between about 12 and 20 inches and preferably 16 inches above the underlying surface 12. This is so that a standard twin or twin xl size mattress may have a top surface upon which the person sleeps upon be about 20 to 32 inches (preferably about 24-27 inches) above the underlying surface 12.

FIGS. 5-16 show a side view of the sofa bed 10 transitioning from a sofa, as shown in FIG. 5, to a bed, as shown in FIG. 16. These figures also illustrate how the folding mechanism 100 and the sliding mechanism 110 of FIG. 17 facilitates the transition. Briefly, the sofa configuration may transition to a bed configuration with the user rotating the backrest 30 so that the rear side 38 faces upward and is parallel to a horizontal plane, and the seat base 50 may be lowered so that the backrest 30 is above the seat base 50. This position is the bed configuration and is shown in FIG. 16. To reverse the transition, the user may pull in the direction of arrow 51 (see FIG. 16) and rotate the backrest 30 upward as shown by arrow 53 in FIG. 16 and raise the seat base 50 along with the backrest 30. These transition processes are briefly touched on here to give context for how the folding and sliding mechanisms 100, 110 operate, and they will be further discussed in detail.

The folding mechanism 100 may be assembled on the sofa bed 10 so that a left first link member 104 and a left second link member 108 are the mirror images of a right first link member 104 and a right second link member 108 about a vertical plane normal to the seat base 50 that bisects the sofa bed 10. The left first and second link members 104, 108 are identical to the right first and second link members but are located on opposite sides of each other. Reference numbers 104, 108 refer to both the first and second link members on the left and right sides. The left and right first link members 104 may be shorter than the left and right second link members 108. The left and right first link members 104 are preferably of a length between 2 inches and 6 inches and most preferably about 3.5 inches, whereas the left and right second link members 108 are preferably of a length between 3 inches to 10 inches and most preferably about 6.5 inches. The link members 104, 108 may be made of a high strength and durable material such as steel or any another material known in the art to have adequate strength and durability. The left and right first link members 104 may be rotatably attached to the left backrest end 32 and the left armrest 20 and the right backrest end 34 and the right armrest 22, respectively. Likewise, the left and right second link members 108 may be rotatably attached to the left backrest end 32 and the left armrest 20 and the right backrest end 34 and the right armrest 22, respectively. The rotatable attachments on the backrest 30 may have pivot points 103 a, 103 b, 103 c, and the rotatable attachments on the seat base 50 may have pivot points 103 d, and the armrests 20, 22 may have pivot points 103 e which may also be referred to as joints in a nonlimiting manner. These pivot points 103 a, 103 b, 103 c, 103 d, 103 e may be in a variety of forms, such as pivot pins, rivets, and bolt and nut combinations. The pivot points 103 a of the rotatable attachment of the left and right first link members 104 to the left and right backrest ends 32, 34 may be at a first height 105 above the underlying surface 12. In the bed configuration, the first height 105 (see FIG. 16) may be equal to or within 6 inches of a second height 109 (see FIG. 16) above the underlying surface 12 where the pivot points 103 b of the rotatable attachment of the left and right second link members 108 to the left and right backrest ends 32, 34 may be located. In the sofa configuration, the first height 105 may be higher than the second height 109 (see FIG. 5).

As shown in FIGS. 5-16, in carrying out the transition from sofa configuration to bed configuration, the folding mechanism 100 may function by left and right first and second link members 104, 108 oscillating the backrest 30 about a left joint 103 b and a right joint 103 b that join the left and right backrest ends 32, 34 to the left and right second link members 108 and a left joint 103 a and a right joint 103 a that join the left and right backrest ends 32, 34 to the left and right first link members 104 until the backrest rear side 38 is facing upward and is parallel to the horizontal plane. The transition motion may stop when the left and right first link members 104 are parallel to the left and right second link members 108 and normal to the underlying surface 12. All link members 104, 108, and thus the backrest 30 may be at rest because the forces acting on their respective pivot points 103 a, 103 b may counter each other and rotational moments may be zero. For example, the moment acting on the backrest due to its combined weight, is counteracted by the reaction force couple generated by the left and right first link members 104 and the left and right second members 108. The folding mechanism 100 is locked and the sofa bed 10 cannot be unintentionally traversed to the sofa configuration once the sofa bed 10 is in the bed configuration. If a user attempts to lift up on the backrest 30 without first pulling the backrest in the direction of arrow 51, the left and right first and second link members 104, 108 lock up, in that they cannot be rotated.

The sliding mechanism 110 may be locked when the sofa bed 10 is in the sofa configuration with a stopping mechanism 120 to further restrict movement of the link members 104, 108, and thus transition of the sofa bed 10 from the sofa configuration to the bed configuration. The sliding mechanism will be further discussed below.

Also in the bed configuration, the left and right first link members 104 may exert a vertical and upward pulling force on the backrest 30 due to the tension applied by the pivot points 103 a where the first link members 104 and armrests 20, 22 attach together. The magnitude of this force may counter the magnitudes of all other vertical forces exerted on the backrest 30 at a downward direction. These forces may be the vertical component of the force exerted by the front link members 60, 62, the weight of the back rest 30, the downward force on the back rest 30 due to the force applied by the pivot points 103 b, where the second link members 108 and armrests 20, 22 attach together, and the weight of the user. Thus, the bed configuration may be in a state of static force equilibrium. This equilibrium may be further reinforced by a stopping mechanism 120 to counter the horizontal as well as the vertical component of the force transferred by the front link members 60, 62 on the backrest 30. The stopping mechanism 120 may lock one, multiple, or all of the following, thereby stopping seat base 50 and the backrest 30 from moving in all directions: the sliding mechanism 110, the front link members 60, 62, or the first and second link members 104, 108. The stopping mechanism 120 may be a spring loaded latch 120 engaging with a latch slot or any other locking mechanism appreciated by those with ordinary skill in the art. There may be an upper latch slot 124 a to allow locking at the sofa configuration and a lower latch slot 124 b to allow locking at the bed configuration. The latch 120 may not pull out or unlock itself out of the slots 124 a, 124 b unless actuated by the user manually or via a control device, such as a button or a switch. The sofa bed 10 may be locked at either the sofa configuration or bed configuration.

Also, as shown in FIGS. 5 and 16 the left and right front link members 60, 62 may hold the seat base 50 at the desired position both in the sofa configuration and the bed configuration. The front link members 60, 62 may be made of a high strength and durable material such as aluminum or another material to have similar strength and durability (e.g., steel). They may preferably have a length between about 5 inches and 20 inches. The left and right front link members 60, 62 may be rotatably attached to the left backrest end 32 and the left seat base end 52 and the right backrest end 34 and the right seat base end 54, respectively. The rotatable attachments may have pivot points 103 c on the backrest 30 and pivot points 103 d on the seat base 50. Pivot points 103 c may be at a first height 64 from the underlying surface 12, whereas pivot points 103 d may be at a second height 66 from the underlying surface 12. The first height 64 may be higher than the second height 66 in both sofa and bed configurations (see FIGS. 5 and 16). These pivot points 103 c, 103 d may be in a variety of forms, such as pivot pins, rivets, and bolt and nut combinations.

In the sofa configuration, the left and right front link members 60, 62 may be static because the locking mechanism is engaged, and thus the backrest 30 may not tip over toward the bed configuration.

Referring now to FIG. 17, the sliding mechanism 110 may be employed to guide the seat base 50 up and down as the sofa bed 10 is transitioned between the sofa and bed configurations. Although a sliding mechanism is described, other mechanisms in lieu of the sliding mechanism may be used. By way of example and not limitation, the sliding mechanism may be replaced with a profile linear bearing, a four-bar linkage, slots and grooves guiding a peg or nub, and other mechanism that limit or governs the seat base up and down as the sofa bed 10 is transitioned between the sofa configuration and bed configuration. The up and down motion governed by the sliding mechanism or alternate mechanism may be linear or curved.

As mentioned above, the sliding mechanism 110 may be locked at a bottom bed configuration position and a top sofa configuration position with a stopping mechanism 120. The sliding mechanism 110 may have left and right first track members 112, 116 and left and right second track members 114, 118 that mirror each other across the vertical plane bisecting the sofa bed 10. The sliding mechanism 110 may have at least one track member or may have at most ten track members on each side. In the figures, two tracks are shown on each side. The two sets of track members 112, 116, 114, 118 described herein is only one embodiment of the invention and is not intended to be limiting in the quantity of track members that may be used in the sliding mechanism 110. The left first and second track members 112, 114 may connect the left seat base end 52 to the left armrest 20, and the right first and second track members 116, 118 may connect the right seat base end 54 to the right armrest 22. First track members 112, 116 may be parallel to second track members 114, 118 and mounted on the left and right armrest inner surfaces 21, 23 at an angle preferably between 6 to 20 degrees to the vertical plane, and most preferably 12 degrees. However, the angle may be any acute angle to the vertical plane that would allow the seat base 50 to travel down a trajectory to its bed configuration position without being offset with the backrest 30 for more than 3 inches at that position. This may be desirable because the seat base 50 may want to be kept tucked away as much as possible to avoid bumping into it or for stylistic reasons. The track members 112, 114, 116, 118 may be actuated into sliding motion with a spring. The spring may be mechanical or pneumatic. The user may convert the sofa bed 10 from one configuration to the other by exerting less energy when moving the seat base 50 either up or down by allowing the spring to bear some or all of the load. The compressibility of the cushions can also serve to help lower the back rest at the end of the stroke where the back rest and the cushions of the seat base contact back rest.

The left and right first and second track members 112, 116, 114, 118 may be further split into left and right first and second rails 113 a, 115 a, 117 a, 119 a and left and right first and second sliding members 113 b, 115 b, 117 b, 119 b. The left rails 113 a, 117 a mirror the right rails 115 a, 119 a along the vertical plane 20 bisecting the sofa bed 10. The first and second rails 113 a, 115 a, 117 a, 119 a may be equal in length. The left and right first and second rails 113 a, 115 a, 117 a, 119 a may be receptive to and slidably engageable with left and right first and second sliding members 113 b, 115 b, 117 b, 119 b. The left and right first and second rails 113 a, 115 a, 117 a, 119 a may be mounted on the left armrest inner surface 21 and right armrest inner surface 23, respectively. The mounting may be so that the first and second rails 113 a, 115 a, 117 a, 119 a may reach between about 7.875 inches to about 23.625 inches, preferably about 15.75 inches, high from the underlying surface 12. The left and right first and second sliding members 113 b, 115 b, 117 b, 119 b may be mounted on the left and right seat base ends 52, 54, respectively.

FIG. 19 shows a flowchart for a method 200 of converting the sofa bed 10 from a sofa configuration to a bed configuration. The method 200 may include a step 202 of unlocking a stopping mechanism 120 that holds the seat base 50 and the backrest 30 at the sofa configuration at both the left and right counterparts of the sliding mechanism 110. The stopping mechanism 120 may be a spring loaded latch 120 that may be unlocked manually or with button or switch controls and may function as described above. Unlocking the spring loaded latch 120 may involve retracting the latch 120 from the upper latch slot 124 a, and thereby rendering the sliding mechanism 110 slideable.

The method 200 may next include a step 204 of rotating the backrest 30 until its rear side 38 defined by the bed frame 40 housing the mattress 42 faces upwards and is parallel to the horizontal plane. This is the bed configuration. To traverse the sofa bed 10 back to the sofa configuration, a pulling force 51 on the backrest 30 may be necessary to initiate the rotation of the backrest. The pulling force 51 skews the link members 104, 108 so that the link members 104,108 can be rotated. When the link members 104, 108 are parallel to each other, they cannot be rotated. In this manner, the sofa bed 10 is locked in the bed configuration even without the stopping mechanism 120.

After step 204 is initiated and the back rest is being transitioned to the bed configuration, the method 200 may also include a step 206 of lowering the seat base 50 so that the backrest 30 is disposed above the seat base 50. This step may be simultaneously executed with step 204. Lowering the seat base 50 may be accomplished with the left and right front link members 60, 62, and the sliding mechanism 110 as described above. The track members 112, 116, 114, 118 may be actuated into sliding motion as described above. A spring could be used to help with the lowering of the back rest 30 and the seat base 50 so that the sofa bed 10 does not too quickly fall into the bed configuration. The spring may carry some of the weight of the back rest 30 and seat base 50 so that the back rest 30 can be gently placed or transitioned to the bed configuration. The compressibility of the cushions can also serve gently place the back rest in the bed configuration at the end portion of the transition from the seat configuration to the bed configuration.

The method 200 may next include a step 208 of positioning the left and right first link members 104 vertical and parallel to the left and right second link members 108 to virtually lock the backrest 30 at the bed configuration as described above. The locking may be further reinforced by locking a stopping mechanism 120 that holds the seat base 50 and the backrest 30 at the bed configuration at both the left and right counterparts of the sliding mechanism 110. The stopping mechanism 120 may be a spring loaded latch 120 that may be locked and may function as described above. Locking the spring loaded latch 120 may involve inserting the latch 120 to the lower latch slot 124 b, and thereby rendering the sliding mechanism 110 non-slidable. Step 208 may be achieved automatically by means of the weight of the back rest and the included mattress.

FIG. 20 shows a flowchart for a method 300 of converting the sofa bed 10 from a bed configuration to a sofa configuration. The method 300 may include a step 302 of pulling a bed frame 40 defined by a backrest 30 laterally to skew left and right first link members 104 to left and right second link members 108 for unlocking the sofa bed 10 from the bed configuration to the sofa configuration. This skewed orientation of the link members 104, 108 may be necessary to allow link members 104, 108 to rotate about their pivot points 103 a, 103 b. The user may initiate the pulling by applying a horizontal pulling force 51 on the backrest 30. This may involve the user standing in front of the sofa bed 10, grabbing the bed frame 40, and pulling the backrest 30 towards the user. The user may stop pulling when the left and right first link members 104 are skewed with respect to each other.

The method 300 may next include a step 304 of rotating the bed frame 40 upward in the direction of arrow 53. This may require the user to apply a vertical pulling force on the backrest 30. The user may achieve this by standing in front of the sofa bed 10, grabbing the bed frame 40, and pulling up on the backrest 30 away from the underlying surface 12.

The method 300 may next include a step 306 of raising the seat base 50. This step may be simultaneously executed with step 304. Raising the seat base 50 may be accomplished with the left and right front link members 60, 62 and the sliding mechanism 110 as described above. The back rest 30 may be assisted toward into the upward motion with a spring as described above. The seat base 50 may also be raised manually, without the assistance of links or springs. For example, the user can apply an upward force onto the seat base 50. If a stopping mechanism 120 is included in the sofa bed 10, then the upward force will move the seat base 50 upward toward the sofa configuration after disengaging the stopping mechanism 120.

The method 300 may next include a step 308 of locking the seat base 50 and the backrest 30 to a sofa configuration. This step may be executed by locking the stopping mechanism 120 at both the left and right counterparts of the sliding mechanism 110. The stopping mechanism 120 may be a spring loaded latch 120 that may be locked and may function as described above. Locking the spring loaded latch 120 may involve inserting the latch 120 to the upper latch slot 124 a, and thereby rendering the sliding mechanism 110 non-slidable. In lieu of or in addition to the stopping mechanism 120, the sofa bed 10 may be retained in the sofa configuration when the center of gravity of the back rest 30 crosses over a rotational point of the back rest 30 which occurs between the link members 104, 108. The weight of the back rest 30 and the distance of the center of gravity of the back rest 30 to the center of gravity creates a moment greater than the weight of the seat base 50 so that even without the stopping mechanism 120 the sofa bed 10 stays in the sofa configuration.

FIGS. 21-23 show partial perspective views of an embodiment a sofa bed 10 having a seat base folding mechanism 68 which transitions the seat base 50 between the up position (see FIG. 34) and the down position (see FIG. 24). The embodiment may be an alternative to the sliding mechanism 110 (see FIG. 1). FIGS. 24-34 show side views of the sofa bed 10 of FIGS. 21-23 with the folding mechanism in various positions as the sofa bed 10 transitions from a bed (see FIG. 24) to a sofa (see FIG. 34). The right portion 22 (see FIG. 1) of the sofa bed 10 is not shown in the partial views of FIGS. 21-34 in order to more clearly visualize the seat base folding mechanism 68, but the right portion 22 is understood to be present in the sofa bed 10 of FIGS. 21-34 as shown through FIG. 1.

Referencing FIG. 21, the seat base folding mechanism 68 may transition the seat base 50 between the up position and the down position simultaneously with transitioning of the sofa bed 10 from a sofa configuration (see FIGS. 21 and 34) and a bed configuration (see FIGS. 22 and 24). That is, rotation of the backrest 30 between the sofa configuration (see FIGS. 21 and 34) and the bed configuration (see FIGS. 22 and 24) also may result in transitioning of the seat base 50 between the up position and the down position.

As described above with respect to FIGS. 1-4, the sofa bed 10 may include a bed frame 40 having left and right portions, such as left and right support members 20, 22 (see FIG. 1), which may also be referred to as left and right armrests 20, 22. It will be appreciated that the term “armrest” is for exemplary purposes only and not intended to be limiting. It is expressly contemplated that the sofa bed 10 may have left and right portions 20, 22 that are not armrests. The left and right portions 20, 22 may be constructed out of one or a combination of materials commonly used in building sofa beds 10 such as wood, artificial wood, molded plastic, aluminum and steel or any other durable, flexible, and/or resilient material. The left and right portions 20, 22 may be further padded and layered with linen fabric, corduroy, or leather depending on stylistic and comfort needs. Materials such as foam, down, feathers, fabric or a combination thereof may be utilized as padding.

The left and right portions 20, 22 of the sofa bed 10 may be understood as mirror images of each other about a vertical plane normal to the seat base 50 that bisects the sofa bed 10. For purposes of explanation and not limitation, discussion of the embodiment of a seat base folding mechanism 68 which transitions the seat base 50 between the up position and the down position are made with respect to the right side of the sofa bed 10. It will be understood that the components shown on the right portion 22 of the sofa bed 10 such as a seat base support member 70 and the seat base folding mechanism 68 may be mirrored on the left portion 20 of the sofa bed 10 (see FIG. 1).

Referencing FIG. 21, the right portion 22 of the sofa bed 10 may include a seat base support member 70. The seat base support member 70 may be understood as being fixed to a right portion 22 of the sofa bed 10. The fixation of the seat base support member 70 may include fastening or adhering the seat base support member 70 to the right portion 22 of the sofa bed 10. Alternatively, the seat base support member 70 may be integrally formed with the right portion 22 of the sofa bed 10 or be an insert that is press fit into a corresponding recess of the right portion 22. The seat base support member 70 may be made of a material such as aluminum, steel, wood, artificial wood, molded plastic, or any other durable, flexible, and/or resilient material. Preferably, the seat base support member 70 may be made of aluminum, steel, or another metal. The seat base support member 70 may be made from the same material as the right portion 22 of the sofa bed 10 to which it is fixed, or the seat base support member 70 may be made from a different material from the right portion 22 of the sofa bed 10. In some embodiments, different metal or metal alloys may be used for the right portion 22 and the seat base support member 70. For example, a harder wearing metal may be used for the seat base support member 70 to ensure longevity of the seat base support member 70.

The seat base support member 70 may be a plate or bar with attachment points for pivotally attaching linkages of the seat base folding mechanism 68. In an exemplary embodiment, the seat base support member 70 may be a rectangular plate. However, the seat base support member 70 is not limited to such shape, as it may be a different geometric shape or integral with the right portion 22 of the sofa bed 10.

With reference to FIG. 22, the seat base support member 70 may comprise three pivot attachments or pivot joints 82 a, 82 b, 82 c to which linkages can be rotatably attached. The term pivot point was previously used above with respect to FIGS. 1-19. With respect to FIGS. 21-34, various pivot joints are described and the term pivot point may refer to a point about which a component rotates or a point which a force vector proceeds through. The various pivot joints may be in a variety of forms, such as bearings, sleeve bearings, pivot pins, rivets, and bolt and nut combinations. The seat base support member 70 may have a first pivot joint 82 a, a second pivot joint 82 b, and a third pivot joint 82 c. Each of the first, second, and third pivot joint 82 a, 82 b, 82 c may have a linkage rotatably attached. In some embodiments, the first, second, and third pivot joints 82 a, 82 b, 82 c may include recesses or openings for fitment of a fastener. In such cases, the recesses or openings may include a ball bearing or sleeve bearing for smooth rotation of an attached linkage.

Referencing FIG. 30, the first, second, and third pivot joints 82 a, 82 b, 82 c may be arranged so that they are collinear as indicated by a straight longitudinal line 81, FIG. 24. A first distance 84 a may be defined as a distance between the first pivot joint 82 a and the second pivot joint 82 b. A second distance 84 b may be defined as a distance between the second pivot joint 82 b and the third pivot joint 82 c. The first distance 84 a and the second distance 84 b may be set to correspond to different widths of the seat base 50. Each of the first and second distances 84 a, 84 b may have a distance ranging from 4 to 20 inches (preferably about 8 inches). In some embodiments, the first distance 84 a may be equal to the second distance 84 b. Alternatively, the first distance 84 a may be different from the second distance 84 b. Accordingly, the seat base support member 70 may have a length 70 a greater than the first and second distances 84 a, 84 b to accommodate the first, second, and third pivot joints 82 a, 82 b, 82 c. The seat base support member 70 may have a length 70 a ranging from 10 inches to 30 inches (preferably about 20 inches).

In some embodiments, the seat base support member 70 is a plate fixed to the right portion 22. Referencing FIG. 22, the seat base support member 70 may have a thickness 70 b that acts as a spacer to allow the rotatably attached linkages to be spaced from the right portion 22. The thickness 70 b may range from 0.125 inch to 1 inch (preferably about 0.5 inch). In this way, the seat base support member 70 can serve to allow the linkages to rotate without friction from contact with the right portion 22 of the sofa bed 10. Alternatively, in embodiments where the seat base support member 70 may be integrally formed with the right portion 22, the seat base support member 70 may have standoffs formed at where the linkages are attached. Separate standalone spacers may also be used in order to provide the spacing. The seat base support member 70 can also be attached to the right portion 20 using a quick-connect mechanism for faster assembly/disassembly.

The sofa bed 10 may have a backrest 30 disposed between the left and right portions 20, 22 of the sofa bed 10 generally as described above with respect to FIGS. 1-19. With reference to FIG. 24, the backrest 30 may have a first backrest pivot joint 103 c. The first backrest pivot joint 103 c may provide for attachment of a fourth linkage 62 as further discussed below. The first backrest pivot joint 103 c may be in a variety of forms, such as pivot pins, rivets, and bolt and nut combinations.

The sofa bed 10 may have a seat base 50 disposed between the left and right portions 20, 22 of the sofa bed 10 generally as described above with respect to FIGS. 1-19. With reference to FIG. 21, the seat base 50 may include a right seat base link support 72. the right seat base link support 72 may be understood as being fixed to a right portion of the seat base 50. The fixation of the seat base link support 72 may include fastening or adhering the seat base link support 72 to the seat base 50. Alternatively, the seat base link support 72 may be integrally formed with the seat base 50 or be an insert that is press fit into a corresponding recess of the seat base 50, or attached via a quick-connect mechanism. The seat base link support 72 may be made of a material such as aluminum, steel, wood, artificial wood, molded plastic, or any other durable, flexible, and/or resilient material. Preferably, the seat base link support 72 may be made of aluminum, steel, or another metal. The seat base link support 72 may be made from the same material as the seat base 50 to which it is fixed, or the seat base link support 72 may be made from a different material from the seat base 50. In some embodiments, different metal or metal alloys may be used for the seat base and the seat base link support 72. For example, a harder wearing metal may be used for the seat base link support 72 to ensure longevity of the seat base link support 72.

The seat base link support 72 may be a plate or bar with attachment points for pivotally attaching linkages of the seat base folding mechanism 68. In an exemplary embodiment, the seat base link support 72 may be a rectangular plate. However, the seat base link support 72 is not limited to such shape, as it may be a different geometric shape or integral with the seat base 50.

With reference to FIG. 22, the seat base link support 72 may comprise three pivot attachments or pivot joints to which linkages can be rotatably attached. The seat base link support 72 may have a fourth pivot joint 82 d, a fifth pivot joint 82 e, and a sixth pivot joint 82 f. Each of the fourth, fifth, and sixth pivot joints 82 d, 82 e, 82 f may have a linkage rotatably attached. These pivot joints 82 d, 82 e, 82 f may be in a variety of forms, such as pivot pins, rivets, and bolt and nut combinations. In some embodiments, the fourth, fifth, and sixth pivot joints 82 d, 82 e, 82 f may include recesses or openings for fitment of a fastener. In such cases, the recesses or openings may include a ball bearing or sleeve bearing for smooth rotation of an attached linkage.

The fourth, fifth, and sixth pivot joints 82 d, 82 e, 82 f may be arranged collinearly along a straight longitudinal line 85. The longitudinal line 85 is parallel to the longitudinal line 81 defined by the first, second, and third pivot joints 82 a, 82 b, 82 c. In view of the seat base support member 70, the seat base link support 72, the first linkage 74, the second linkage 76, and the third linkage 78, the first, second, third, fourth, fifth, and sixth pivot joints 82 a, 82 b, 82 c, 82 d, 82 e, 82 f may define a five bar parallelogram structure.

With reference to FIG. 29, a third distance 84 c may be defined as a distance between the fourth pivot joint 82 d and the fifth pivot joint 82 e. A fourth distance 84 d may be defined as a distance between the fifth pivot joint 82 e and the sixth pivot joint 82 f. The third distance 84 c and the fourth distance 84 d may be set to correspond to different widths of the seat base 50. Each of the third and fourth distances 84 c, 84 d may have a distance ranging from 4 to 20 inches (preferably about 8 inches). In some embodiments, the third distance 84 c may be equal to the fourth distance 84 d. Alternatively, the third distance 84 c may be different from the fourth distance 84 d. Accordingly, the seat base link support 72 may have a length 72 a greater than the third and fourth distances 84 c, 84 d to accommodate the fourth, fifth, and sixth pivot joints 82 d, 82 e, 82 f. The third distance 84 c is equal to the first distance 84 a (see FIG. 30) of the seat base support member 70. The fourth distance 84 d is equal to the second distance 84 b of the seat base support member 70. The seat base link support 72 may have a length 72 a ranging from 10 inches to 30 inches (preferably about 20 inches).

Referencing FIG. 23, the fourth, fifth, and sixth pivot joints 82 d, 82 e, 82 f can also include spacers 80 to separate attached linkages from the seat base link support 72. A thickness of the spacers 80 may correspond to approximately the thickness of the fourth linkage 62. The thickness of the spacers 80 may range from 0.125 inch to 1 inch (preferably about 0.5 inch). The fourth, fifth, and sixth pivot joints 82 d, 82 e, 82 f may each provide a gap to the seat base link support 72 from each of a first linkage 74, a second linkage 76, and a third linkage 78. In this way, the first linkage 74, the second linkage 76, and the third linkage 78 of the folding mechanism 68 can be arranged in a coplanar arrangement with the gaps being filled by the spacers 80. Further described below, the gap between the base seat link support 72 and the first linkage 74 allows for a fourth linkage 62 and a seventh pivot joint 103 d to be disposed between the first linkage 74 and the seat base link support 72. Further more, the spacers could be integrated onto the structure of the supports 70 and 72, as an embossed or raised offset around the pivot points.

Also, the seat base link support 72 may be a plate fixed to the seat base 50. The seat base link support 72 may have a thickness 72 b that acts as a spacer 80 to allow the rotatably attached linkages to be spaced from the seat base 50. The thickness 72 b may range from 0.125 inch to 1 inch (preferably about 0.5 inch). In this way, the seat base link support 72 can serve to allow the fourth linkage 62 to rotate without friction from contact with the seat base 50. Alternatively, in embodiments where the seat base link support 72 may be integrally formed with the seat base 50, the seat base link support 72 may have standoffs formed at where the linkages are attached. The standoffs may have a thickness ranging from 0.125 inch to 1 inch (preferably about 0.5 inch).

With reference to FIG. 21, the sofa bed 10 includes the seat base folding mechanism 68 which transitions the seat base 50 between the up position and the down position. The seat base folding mechanism 68 may include a right first linkage 74 rotatably attached to the right portion 22 of the sofa bed 10 and the right end portion of the seat base 50. Referencing FIG. 22, the first linkage 74 may be pivotally attached to the seat base support member 70 at the first pivot joint 82 a. The first linkage 74 may be rotatably attached to the seat base link support 72 at the fourth pivot joint 82 d.

Referencing FIG. 25, the fourth pivot joint 82 d of the first linkage 74 may rotate along a circular path 91 about the first pivot joint 82 a which is fixed to the right portion 22 of the sofa bed 10 (see FIGS. 24-34). The circular path 91 is shown in FIG. 28 for purposes of clarity and not limitation. As the first linkage 74 rotates about the first pivot joint 82 a, the seat base 50 which is attached to the first linkage 74 is also thereby moved in accordance with the circular path of the fourth pivot joint 82 d of the first linkage 74.

The first linkage 74 may have a seventh pivot joint 103 d. The term pivot point 103 d was previously used above with respect to FIGS. 1-19 for a pivot point of the front link members 60, 62 to the seat base 50. In FIGS. 21-34, the fourth linkage 62 may not be directly attached to the seat base. However, the fourth linkage 62 is indirectly attached to seat base 50 via the first linkage 74 through the seventh pivot joint 103 d. That is, the first linkage 74 has three attachment pivot joints. The three attachment pivot joints include the first pivot joint 82 a, the fourth pivot joint 82 d, and the seventh pivot joint 103 d.

Referencing FIG. 25, the first linkage 74 may have a J or L shape made up of two portions 73, 75. The two portions 73, 75 are shown as being straight. However, other configuration are also contemplated including but not limited to curved. The first linkage 74 may have a first portion 73 between the first pivot joint 82 a and the fourth pivot joint 82 d. The first linkage 74 may have a second portion 75 between the fourth pivot joint 82 d and the seventh pivot joint 103 d. In other embodiments, the first linkage 74 may have alternative geometric shapes, such as a triangular plate or curved sections.

A first linear axis 92 of the first portion 73 is defined between the first pivot joint 82 a and the fourth pivot joint 82 d. A second linear axis 94 of the second portion 75 is defined between the fourth pivot joint 82 a and a seventh pivot joint 103 d. The first linear axis 92 and the second linear axis 94 may be arranged at an angle ranging from 1 degree to 180 degrees (preferably about 120 degrees).

A first distance 74 a of the first linkage 74 may be defined between the first pivot joint 82 a and the fourth pivot joint 82 d. The first distance 74 a of the first linkage 74 may range from 3 to 18 inches (preferably about 8 inches). A second distance 74 b of the first linkage 74 may be defined between the first pivot joint 82 a and the seventh pivot joint 103 d. The second distance 74 b may be greater than the first distance 74 a. By having a greater distance from first pivot joint 82 a, the length of the first linkage 74 defined by the second distance 74 b provides a longer moment arm than the first distance 74 a. As the second distance 74 b increases, less force would be needed to act on the seventh pivot 103 d for a given torque about the first pivot joint 82 a to transition the seat base from the down position to the up position. The second distance 74 b may be greater than the first distance 74 a in a range from 1 inch to 6 inches (preferably about 1.5 inch).

Alternatively, the second distance 74 b may be less than or equal to the first distance 74 a. By way of example and not limitation, the seventh pivot joint 103 d can be coaxially aligned to the fourth pivot joint 82 d so that the second distance 74 b is equal to the first distance 74 a. Alternatively, the second section 75 may have a U configuration such that the second distance 74 b is less than the first distance 74 a.

The first linkage 74 may also define a third distance 74 c between the first pivot joint 82 a and an opposed distal end 77 of the first linkage 74 beyond the seventh pivot joint 103 d. This third distance 74 c is less than the first distance 84 a of the seat base support member 70. The third distance 74 c may range from 4 to 20 inches (preferably about 7 inches). The distal end 77 which defines the third distance 74 c may travel along a circular path 93. As shown in FIGS. 26-28, the third distance 74 c is sufficiently short so that as the first linkage 74 rotates the seat base 50 from below the second pivot joint 82 b to above the second pivot joint 82 b. As shown in FIGS. 25 and 27, due to the third distance 74 c being shorter than the first distance 84 a, there is a clearance 96 a such that the first linkage 74 does not contact the second pivot joint 82 b (see FIGS. 26-28). Moreover, the second pivot joint 82 b may comprise a bearing, sleeve bearing or other structure to allow for the rotation of the first linkage 74. The third distance 74 c may be sufficiently short so that there is also clearance between the distal end 77 and the structure of the second pivot joint 82 b.

The second portion 75 of the first linkage 74 may define a length 74 d from the fourth pivot joint 82 d to the seventh pivot joint 103 d ranging from 1 inch to 6 inches (preferably about 2 inches). The first distance 74 a may be a multiple of the length 74 d ranging from 1 to 10 times that length 74 d (preferably about 4).

The first linkage 74 may have a thickness ranging from 0.125 inch to 1 inch (preferably about 0.5 inch). The first linkage 74 may be made of a material such as aluminum, steel, wood, artificial wood, molded plastic, or any other durable, flexible, and/or resilient material. Preferably, the first linkage 74 may be made of aluminum, steel, or another metal.

Referencing FIG. 34, in some embodiments, there may be a stopping mechanism 120 that contacts the first linkage 74 to limit the rotation of the first linkage 74 in the first rotational direction 95 when the sofa bed 10 is transitioned to the sofa configuration. In order to aid in clarity and visualization of the seat base folding mechanism 68 in the FIGS. 21-33, the stopping mechanism 120 is only shown in FIG. 34. However, it is understood that the stopping mechanism 120 may be part of the sofa bed 10 shown in all of the partial views of FIG. 21-33. As shown in FIG. 34 for purposes of explanation and not limitation, the stopping mechanism 120 may extend laterally from the right portion 22 of the sofa bed 10 to contact the seat base 50 and the first linkage 74 and prevent over-rotation. However, the stopping mechanism 120 may contact only one of the seat base 50 and the first linkage 74. This stopping mechanism 120 may be the limit of rotation in the first rotational direction 95 in the sofa configuration. The stopping mechanism 120 can be positioned to contact the seat base 50 or the first linkage 74 when the seat base 50 is in the up position. The stopping mechanism 120 may be a protrusion projecting from the right portion 22 of the sofa bed 10. The stopping mechanism 120 may be a geometric shape such as a rectangle. In some embodiments, the stopping mechanism 120 may be a rectangular block extending laterally from the right portion 22 of the sofa bed 10. It can also be integrated as a feature of support link 70, or be a stop for the backrest 30 as well.

With reference to FIG. 21, the seat base folding mechanism 68 may include a right second linkage 76 rotatably attached to the right portion 22 of the sofa bed 10 and the right end portion of the seat base 50. Referencing FIG. 26, the second linkage 76 may be pivotally attached to the seat base support member 70 at the second pivot joint 82 b. The second linkage 76 may be rotatably attached to the seat base link support 72 at the fifth pivot joint 82 e. The fifth pivot joint 82 e of the second linkage 76 can rotate along a circular path about the second pivot joint 82 b which is fixed to the right portion 22 of the sofa bed 10. As the second linkage 76 rotates about the second pivot joint 82 b, the seat base 50 which is attached to the second linkage 76 is also thereby moved in accordance with the circular path of the second linkage 76.

A first distance 76 a of the second linkage 76 may be defined between the second pivot joint 82 b and the fifth pivot joint 82 e. The first distance 76 a of the second linkage 76 is the same as the first distance 74 a of the first linkage 74 (see FIG. 25). The first distance 76 a of the second linkage 76 may range from 3 to 18 inches (preferably about 8 inches).

The second linkage 76 may also define a second distance 76 b between the second pivot joint 82 b and an opposed distal end 79 of the second linkage 76 beyond the fifth pivot joint 82 e. The distal end 79 which defines the second distance 76 b may travel along a circular path 99 (see FIG. 28). This second distance 76 b of the second linkage 76 is less than the second distance 84 b of the seat base support member 70. In having the second distance 76 b be less than the second distance 84 b between the second pivot joint 82 b and the third pivot joint 82 c, there can be a clearance gap 96 b (see FIG. 27) such that the second linkage 76 can freely rotate without contacting the third pivot joint 82 c. The second distance 76 b may range from 4 to 20 inches (preferably about 7 inches). The second distance 76 b may define a radius of the circular path of the second linkage 76. As shown in FIGS. 26-28, the second distance 76 b is sufficiently short so that as the second linkage 76 rotates the seat base 50 from below the third pivot joint 82 c to above the third pivot joint 82 c without contacting the third pivot joint 82 c. Moreover, the third pivot joint 82 c may comprise a bearing, sleeve bearing or other structure to allow for the rotation of the second linkage 76. The second distance 76 b may be sufficiently short so that there is also clearance between the distal end 79 and the structure of the third pivot joint 82 c.

Referencing FIG. 26, the second linkage 76 may have a straight section between the second pivot joint 82 b and the fifth pivot joint 82 e. In other embodiments, the second linkage 76 may have alternative geometric shapes, such as a triangular plate or curved sections.

The second linkage 76 may have a thickness ranging from 0.125 inch to 1 inch (preferably about 0.5 inch). The second linkage 76 may be made of a material such as aluminum, steel, wood, artificial wood, molded plastic, or any other durable, flexible, and/or resilient material. Preferably, the second linkage 76 may be made of aluminum, steel, or another metal.

With reference to FIG. 21, the seat base folding mechanism 68 may include a right third linkage 78 rotatably attached to the right portion 22 of the frame and the right end portion of the seat base 50. Referencing FIG. 28, the third linkage 78 may be pivotally attached to the seat base support member 70 at the third pivot joint 82 c. The third linkage 78 may be rotatably attached to the seat base link support 72 at the sixth pivot joint 82 f. The sixth pivot joint 82 f of the third linkage 78 can rotate along a circular path about the third pivot joint 82 c which is fixed to the right portion 22 of the sofa bed 10. As the third linkage 78 rotates about the third pivot joint 82 c, the seat base 50 which is attached to the third linkage 78 is also thereby moved in accordance with the circular path of the third linkage 78.

A first distance 78 a of the third linkage 78 may be defined between the third pivot joint 82 c and the sixth pivot joint 82 f. The first distance 78 a of the third linkage 78 is the same as each of the first distance 74 a of the first linkage 74 (see FIG. 25) and the first distance 76 a of the second linkage 76 (see FIG. 26). The first distance 78 a of the third linkage 78 may range from 3 to 18 inches (preferably about 8 inches).

In an exemplary embodiment, the third linkage 78 may have a straight section between the third pivot joint 82 c and the sixth pivot joint 82 f. In other embodiments, the third linkage 78 may have alternative geometric shapes, such as a triangular plate or curved sections.

The third linkage 78 may have a thickness ranging from 0.125 inch to 1 inch (preferably about 0.5 inch). The third linkage 78 may be made of a material such as aluminum, steel, wood, artificial wood, molded plastic, or any other durable, flexible, and/or resilient material. Preferably, the third linkage 78 may be made of aluminum, steel, or another metal.

Referencing FIG. 21, the first linkage 74, the second linkage 76, the third linkage 78, the seat base support member 70, and the seat base link support 72 can thereby form a five bar parallelogram linkage. As the first, second, and third linkages 74, 76, 78 all have a same first distance 74 a (see FIG. 25), 76 a (see FIG. 26), 78 a (see FIG. 28) and all rotate about their respective pivot joints 82 a, 82 b, 82 c attached to the seat base support member 70, the attached seat base link support 72 is moved in accordance with the circular paths of the fourth, fifth, and sixth pivot joints 82 d, 82 e, 82 f. As such, the seat base 50 is, in its entirety, moved along a circular path.

Referencing FIG. 24, the first, second, and third linkages 74, 76, 78 synchronously rotate at a same rate of rotation (see FIGS. 24-34). When the first, second, and third linkages 74, 76, 78 rotate to transition the seat base 50 from the down position to the up position, the rotation of the first, second, and third linkages 74, 76, 78 can be considered as rotation in a first rotational direction 95. Referencing FIG. 34 when the seat base 50 moves from the up position to the down position, the rotation of first, second, and third linkages 74, 76, 78 can be considered as rotation in a second rotational direction 97. Referencing FIG. 24 in transitioning the seat base 50 from the down position to the up position, a range of rotation of each of the first, second, and third linkages 74, 76, 78 about the first, second and third pivot joints 82 a, 82 b, 82 c may be from 90 degrees to 270 degrees (preferably about 145 degrees).

In transitioning the seat base 50 from the down position (see FIG. 24) to the up position (see FIG. 34), the fourth, fifth, and sixth pivot joints 82 d, 82 e, 82 f can be understood as moving (see FIGS. 24-34) from one side of a horizontal plane 83 defined by the first, second and third pivot joints 82 a, 82 b, 82 c to the other side of the horizontal plane. That is, the fourth, fifth, and sixth pivot joints 82 d, 82 e, 82 f are moved from below the first, second and third pivot joints 82 a, 82 b, 82 c to above.

Referencing FIG. 24, the fourth, fifth and sixth pivot joints 82 d, 82 e, 82 f are positioned on first sides of first, second and third vertical planes 130, 132, 134 defined at first, second and third pivot joints 82 a, 82 b, 82 c in the bed configuration. In embodiments of the bed configuration, the first, second and third linkages 74, 76, 78 may be in a skewed orientation from a respective vertical axis from the first, second, and third pivot points 82 a, 82 b, 82 c. Referencing FIG. 34 and the sofa configuration, the fourth, fifth and sixth pivot joints 82 d, 82 e, 82 f are positioned on second opposite sides of first, second and third vertical planes 130, 132, 134 (see FIG. 34). This is so that when a user sits on the seat base 50 in the sofa configuration, a downward force due to the user sitting provides a rotational moment in the first rotational direction 95. In other words, the seat base 50 stays in the sofa configuration and does not rotate in the second rotational direction 97 to collapse back into the bed configuration. In the sofa configuration, the fourth, fifth and sixth pivot joints 82 d, 82 e, 82 f may be arranged to have a positive angle from vertical in the first rotational direction 95 ranging from 1 to 40 degrees (preferably about 10 degrees).

With reference to FIG. 21, the seat base folding mechanism 68 may include a right fourth linkage 62 rotatably attached to the right end portion of the backrest 30 and the seat base 50. The fourth linkage 62 may be pivotally attached to the backrest 30 at the first backrest pivot joint 103 c. The fourth linkage 62 may be rotatably attached to the seat base 50 via the seventh pivot joint 103 d. A distance between the first backrest pivot joint 103 c and the seventh pivot joint 103 d may range from 4 to 20 inches (preferably about 10 inches).

The fourth linkage 62 may be directly attached to the first linkage 74 at the seventh pivot joint 103 d. The fourth linkage 62 may directly attach to the second portion 75 of the first linkage 74 (see FIG. 25). As described above with respect FIG. 25 and the first linkage 74, the first linkage 74 may have a J or L shape made up of two portions 73, 75. The first distance 74 a of the first linkage 74 may be defined between the first pivot joint 82 a and the fourth pivot joint 82 d. The first distance 74 a of the first linkage 74 may range from 3 to 18 inches (preferably about 8 inches). The first linear axis 92 of the first portion 73 is between the first pivot joint 82 a and the fourth pivot joint 82 d. The second linear axis 94 of the second portion 75 is between the first pivot joint 82 a and a seventh pivot joint 103 d. The first linear axis 92 and the second linear axis 94 may be arranged at an angle ranging from 1 degree to 180 degrees (preferably about 120 degrees).

In the bed configuration as shown in FIG. 24, the linear axis 92 defined by the first pivot joint 82 a and the fourth pivot joint 82 d has a positive angle 87 in relation to the first rotational direction 95 relative to a second linear axis 98 defined by the first backrest pivot joint 103 c and the seventh pivot joint 103 d. As such, an upward force applied through the first backrest pivot joint 103 c will result in rotation of the first linkage 74 in the first rotational direction 95 to transition the sofa bed 10 from the bed configuration (see FIG. 24) to the sofa configuration (see FIG. 34).

In the sofa configuration shown in FIG. 34, the linear axis 92 defined by the first pivot joint 82 a and the fourth pivot joint 82 d has a negative angle 89 in relation to the first rotational direction 95 relative to the second linear axis 98 defined by the first backrest pivot joint 103 c and the seventh pivot joint 103 d. Such a configuration may thereby provide a rotational moment in the second rotational direction 97 when the backrest is transitioned from the sofa configuration (see FIG. 34) to the bed configuration (see FIG. 24), thereby moving the seat base 50 from the up position to the down position.

Referencing FIG. 24, some embodiments may have the positive angle 87 in relation to the first rotational direction 95 and the negative angle 89 by positioning the first backrest pivot joint 103 c between a vertical axis 88 of the first pivot joint 82 a and a vertical axis 90 of the second pivot joint 82 b of the seat base support member 70 that are normal to the longitudinal line 81 defined by first, second, and third pivot joints 82 a, 82 b, 82 c of the seat base support member 70 when in the bed configuration.

The fourth linkage 62 may have a thickness ranging from 0.125 inch to 1 inch (preferably about 0.5 inch). The fourth linkage 62 may be made of a material such as aluminum, steel, wood, artificial wood, molded plastic, or any other durable, flexible, and/or resilient material. Preferably, the fourth linkage 62 may be made of aluminum, steel, or another metal.

In an exemplary embodiment, the fourth linkage 62 may have a straight section between the first backrest pivot joint 103 c and the seventh pivot joint 103 d. In other embodiments, the fourth linkage 62 may have alternative geometric shapes, such as a triangular plate or curved sections.

Accordingly, embodiments of the seat base folding mechanism 68 provide that the first, second and third linkages 74, 76, 78 are disposed between the seat base 50 and the right portion of the frame.

FIG. 35 illustrates a flowchart for a method 400 of transitioning the seat base 50 from a down position to an up position when transitioning a convertible sofa bed 10. The method 400 may include a step 402 of pulling the backrest 30 by applying a lateral or horizontal force on the backrest 30. As described above in step 302 of FIG. 20, step 402 may unlock the sofa bed 10 by allowing a back rest folding mechanism 100 to unlock.

The method 400 may include a step 404 of pulling up on a backrest 30 when the sofa bed 10 is in the bed configuration to transition the sofa bed 10 to the sofa configuration. By pulling up on the backrest 30, the user rotates the backrest 30 from the bed configuration in the first rotational direction 95. The rotation of the backrest 30 as a result of the upward force may be accomplished by a backrest folding mechanism 68.

The method 400 may include a step 406 of transferring a force from the backrest 30 to a seat base 50 through the fourth linkage 62 attached to the backrest 30 and the seat base 50. The pulling up on the backrest 30 and rotation of the backrest 30 may then result in an upward force transmitted through the first backrest pivot joint 103 c to the fourth linkage 62. This then results in an upward force transferred by the fourth linkage 62 to the seventh pivot joint 103 d to the seat base folding mechanism 68.

The method 400 may include a step 408 of rotating the first linkage 74, the second linkage 76, and the third linkage 78. Due to the positive angle in the first rotational direction 95 between the first and fourth pivot joints 82 a, 82 d of the first linkage 74 relative to the first backrest pivot joint 103 c and the seventh pivot joint 103 d of the fourth linkage 62, the first linkage 74, the second linkage 76, and the third linkage 78 are rotated in the first rotational direction 95 due to the upward force. The first linkage 74, the second linkage 76, and the third linkage 78 may rotate at a same rate of rotation throughout an entire rotational travel of the seat base 50 as the seat base 50 is transitioned from a down position to an up position. As such, the rotation of the first linkage 74, the second linkage 76, and the third linkage 78 in the first rotational direction 95 moves the seat base 50 from the down position to the up position.

To prevent over-rotation in the first rotational direction 95, the method 400 may include a step 410 of contacting a stopping mechanism 120 with the seat base 50. The stopping mechanism 120 may be a physical limit of rotation in the first rotational direction 95 in the sofa configuration. The stopping mechanism 120 may be positioned to contact the seat base 50 when the seat base 50 is in the up position. The stopping mechanism 120 may be a protrusion projecting from one of the left and the right portions 20, 22 of the sofa bed 10. The stopping mechanism 120 may be a geometric shape such as a rectangle or a round pin. In some embodiments, the stopping mechanism 120 may be a rectangular block extending laterally from the left or the right portion 20, 22 of the sofa bed 10. In other embodiments it could be an integrated stop in the bed folding mechanism 100.

The method steps of the method 400 may not all be necessary nor performed in sequentially.

FIG. 36 illustrates a flowchart for a method 500 of transitioning the seat base 50 from an up position to a down position when transitioning a convertible sofa bed 10. The method 500 may include a step 502 of rotating the backrest 30 in the second rotational direction 97. The backrest 30 may be rotated from the sofa configuration to the bed configuration where the backrest 30 is horizontal.

The method 500 may include a step 504 of transferring a force from the backrest 30 to a seat base 50 through the fourth linkage 62 attached to the backrest 30 and the seat base 50. The rotation of the backrest 30 in the second rotational direction 97 may result in a force transmitted through the first backrest pivot joint 103 c to the fourth linkage 62. This then results in a force transferred by the fourth linkage 62 to the seventh pivot joint 103 d to the seat base folding mechanism 68.

The method 500 may include a step 506 of rotating the first linkage 74, the second linkage 76, and the third linkage 78 in the second direction 97. Due to the positive angle in the first rotational direction 95 between the first backrest pivot joint 103 c and the seventh pivot joint 103 d of the fourth linkage 62 relative to the first and fourth pivot joints 82 a, 82 d of the first linkage 74 in the sofa configuration, the first linkage 74, the second linkage 76, and the third linkage 78 are rotated in the second rotational direction 97 due to the rotation of the backrest 30 in the second direction. The first linkage 74, the second linkage 76, and the third linkage 78 may rotate at a same rate of rotation throughout an entire rotational travel of the seat base 50 as the seat base 50 is transitioned from a down position to an up position. As such, the rotation of the first linkage 74, the second linkage 76, and the third linkage 78 in the second rotational direction 97 moves the seat base 50 from the up position to the down position.

The method 500 may include a step 508 of pushing the backrest 30 by applying a lateral or horizontal force on the back rest 30. As described above in step 208 of FIG. 19, step 508 may lock the sofa bed 10 by positioning a back rest folding mechanism 100 to have vertical linkages. This may be done automatically by the weight of the back rest 30 without human intervention. In this regard, no pushing would be involved.

The detailed description set forth below in connection with the appended drawings is intended as a description of certain embodiments of the present disclosure and is not intended to represent the only forms that may be developed or utilized. Additional combinations of methods of making sofa beds and of using the sofa beds as described herein are within the scope of the present invention. The description sets forth the various functions in connection with the illustrated embodiments, but it is to be understood, however, that the same or equivalent functions may be accomplished by different embodiments that are also intended to be encompassed within the scope of the present disclosure. It is further understood that the use of relational terms such as “top,” “bottom,” “left,” “right,” “first,” “second,” and the like are used solely to distinguish one entity from another without necessarily requiring or implying any actual such relationship or order between such entities. Also, where used, the terms “secured,” “attached,” connected,” “mounted,” “coupled,” and the like can mean either direct or indirect attachment or contact between elements, unless stated otherwise.

The term “user” used throughout the disclosure may refer to a person performing the method of transitioning the sofa bed between the bed configuration and the sofa configuration. The terms “left” and “right” used throughout the disclosure may reference to the sofa bed as viewed from the user or a person viewing the sofa bed from a seating side when the sofa bed is in the sofa configuration, but the orientation may be reversed.

The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein, including various ways of attaching the folding mechanisms to the support members. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.

Reference in this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The appearance of the phrase “in an embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but not for other embodiments. 

What is claimed is:
 1. A convertible sofa bed with a rotatable backrest disposable between a sofa configuration and a bed configuration, wherein rotation of the backrest transitions a seat base between an up position and a down position, the sofa bed comprising: a frame comprising a left portion and a right portion; the backrest being disposed between the left and right portions of the frame; a seat base comprising a left end portion and a right end portion, the seat base being disposed between the left and right portions of the frame; a folding mechanism which transitions the seat base between the up position and the down position, the folding mechanism comprising: a right first linkage rotatably attached to the right portion of the frame and the right end portion of the seat base; a right second linkage rotatably attached to the right portion of the frame and the right end portion of the seat base; a right third linkage rotatably attached to the right portion of the frame and the right end portion of the seat base; and a right fourth linkage rotatably attached to a right end portion of the backrest and the seat base.
 2. The convertible sofa bed according to claim 1, wherein the right first linkage is rotatably attached to the right portion of the frame at a first pivot joint and to the right end portion of the seat base at a second pivot joint, the right first linkage rotating in a first rotational direction when the convertible sofa bed transitions from a bed configuration to a sofa configuration; wherein the right fourth linkage is rotatably attached to the right end portion of the backrest at a third pivot joint and to the seat base at a fourth pivot joint; wherein in the bed configuration, a first linear axis defined by the first pivot joint and the second pivot joint has a positive angle in relation to the first rotational direction relative to a second linear axis defined by the third pivot joint and the second pivot joint; and wherein in the bed configuration, an upward force on the right fourth linkage results in rotation of the right first linkage in the first rotational direction.
 3. The convertible sofa bed according to claim 1, wherein the right first linkage, the right second linkage, and the right third linkage synchronously rotate at a same rate of rotation.
 4. The convertible sofa bed according to claim 1, wherein the seat base, the right portion of the frame, the right first linkage, the right second linkage, and the right third linkage define a five bar parallelogram linkage.
 5. The convertible sofa bed according to claim 1, wherein the right first linkage is rotatably attached to the right portion of the frame at a first pivot joint and to the right end portion of the seat base a fourth pivot joint; wherein the right second linkage is rotatably attached to the right portion of the frame at a second pivot joint and to the right end portion of the seat base a fifth pivot joint; wherein the right third linkage is rotatably attached to the right portion of the frame at a third pivot joint and to the right end portion of the seat base a sixth pivot joint; wherein the first pivot joint, the second pivot joint, and the third pivot joint are located collinearly along a first axis; and wherein the fourth pivot joint, the fifth pivot joint, and the sixth pivot joint are located collinearly along a second axis.
 6. The convertible sofa bed according to claim 5, wherein in the bed configuration, the fourth, fifth and sixth pivot joints are positioned on first sides of first, second and third vertical planes defined at first, second and third pivot joints, and in the sofa configuration, the fourth, fifth and sixth pivot joints of the first, second and third linkages are positioned on a second opposite sides of first, second and third vertical planes.
 7. The convertible sofa bed according to claim 5, wherein a first distance between the first pivot joint and the fourth pivot joint is equal to each of a second distance between the second pivot joint and the fifth pivot joint and a third distance between the third pivot joint and the sixth pivot joint.
 8. The convertible sofa bed according to claim 5, wherein the right first linkage is rotatably attached to the right portion of the frame at a first pivot joint, the first pivot joint being fixed in position to the right portion of the frame, and the fourth pivot joint of the right first linkage rotates about the first pivot joint along a circular path.
 9. The convertible sofa bed according to claim 8, wherein the right first linkage has a first length from the first pivot joint to a farthest distal end beyond a seventh pivot joint of the right first linkage; wherein the right second linkage has a second length from the second pivot joint to a farthest distal end; wherein a distance between the first pivot joint of the right first linkage and the second pivot joint of the right second linkage defines a first distance; wherein a distance between the second pivot joint of the right second linkage and the third pivot joint of the right third linkage defines a second distance; and wherein the first length of the right first linkage is less than the first distance between the first pivot joint and the second pivot joint such that the right first linkage clears the right second linkage when pivoting along the circular path; wherein the second length of the right second linkage is less than the second distance between the second pivot joint and the third pivot joint such that the right second linkage clears the right third linkage when pivoting along the circular path.
 10. The convertible sofa bed according to claim 1, wherein a range of rotation of the right first linkage between the up position and the down position of the seat base is from 90 degrees to 270 degrees.
 11. A method of transitioning a convertible sofa bed from a bed configuration to a sofa configuration, the method comprising the step of: pulling up on a backrest when the convertible sofa bed is in the bed configuration to transition the convertible sofa bed to the sofa configuration; transferring a force from the backrest to a seat base through a right fourth linkage attached to the back rest and the seat base; rotating a right first linkage, a right second linkage, and a right third linkage at a same rate of rotation throughout an entire rotational travel of the seat base as the seat base is transitioned from a down position to an up position.
 12. The method of claim 11, wherein the step of rotating further comprises synchronously rotating the right first linkage, the right second linkage and the right third linkage in the same rotational direction.
 13. The method according to claim 11, further comprising fixing a first pivot joint which the right first linkage rotates about to the right portion of the frame such that the right first linkage rotates about the first pivot joint along an arcuate portion of a circular path.
 14. The method according to claim 11, further comprising rotating the right first linkage between the up position and the down position of the seat base through a range of rotation from 90 degrees to 270 degrees.
 15. The method according to claim 11, wherein in the bed configuration, the first, second and third linkages are in a skewed orientation from vertical.
 16. The method according to claim 11, wherein the right first linkage is rotatably attached to the right portion of the frame at a first pivot joint and to the right end portion of the seat base a fourth pivot joint; wherein the right second linkage is rotatably attached to the right portion of the frame at a second pivot joint and to the right end portion of the seat base a fifth pivot joint; wherein the right third linkage is rotatably attached to the right portion of the frame at a third pivot joint and to the right end portion of the seat base a sixth pivot joint; wherein the first pivot joint, the second pivot joint, and the third pivot joint are located collinearly along a first axis; and wherein the fourth pivot joint, the fifth pivot joint, and the sixth pivot joint are located collinearly along a second axis.
 17. The method according to claim 16, wherein in the bed configuration, the fourth, fifth and sixth pivot joints are positioned on first sides of first, second and third vertical planes defined at first, second and third pivot joints, and in the sofa configuration, the fourth, fifth and sixth pivot joints of the first, second and third linkages are positioned on a second opposite sides of first, second and third vertical planes.
 18. The method according to claim 16, wherein a first distance between the first pivot joint and the fourth pivot joint is equal to each of a second distance between the second pivot joint and the fifth pivot joint and a third distance between the third pivot joint and the sixth pivot joint.
 19. The method according to claim 11, wherein the right first, second and third linkages are disposed between the seat base and the right portion of the frame.
 20. The method according to claim 16, wherein the seat base, the right portion of the frame, the right first linkage, the right second linkage, and the right third linkage define a five bar parallelogram linkage. 